Filtration systems are used to remove impurities from a stream of fluid such as from air for use in downstream systems. For example, air may be filtered prior to entering an internal combustion engine. In such a system, the filtration system will often include a replaceable filter element that performs the filtration, which can be replaced with a new filter once the filter element is filled with impurities or otherwise becomes spent.
One particular type of filter element uses fluted filter media that is wound to form a filter media pack. In some instances, the fluted filter media is wound around a winding core to form a plurality of layers. Further, the filter media pack may often take non-round shapes such as race-track shaped. These non-round shapes are typically formed by winding the fluted filter media around a thin rectangular core.
However, as the non-round filter media pack is rotated to wind the fluted filter media about the winding core, the force applied from the winding core to the fluted filter media from the thinner sides of the winding core, as opposed to the wider faces of the winding core, is applied to a smaller area of the fluted filter media which can undesirably crush individual ones of the flutes proximate the thinner sides of the winding core.
Another problem related to wound filter media packs is that as the filter media pack is wound, the adjacent layers of wound fluted filter media can slip relative to one another due to the tension during the winding process. This slippage can further damage the flutes of the filter media, such as by way of reducing the open cross-sectional area of the flutes thereby reducing the desired flow characteristics of the resulting filter media pack. The slippage can also degrade the quality of the seal bead that is applied between the adjacent layers of fluted filter media
The present invention relates to improvements over the current state of the art as it relates to wound filter media packs.